Hi thanks for the reply
I think this has now worked, though I still haven't got my cd-r dvd-r working as yet, I have made the change you recommend.
I don't know what is going through Redhat's mind at the moment but of course the files aren't where you said even though I just did an out of the box standard server install. If anyone else using Redhat 8 wants to do this the file is available in two places /etc/grub.conf and /boot/grub/grub.conf. This is the same file with a symbolic link to /etc/grub.conf.
Now to work out the rest of the puzzle.